Busbar, motor, and power transmission system using same

ABSTRACT

Disclosed in one embodiment is a busbar comprising: an insulating body; a plurality of neutral terminals arranged in the insulating body; and a plurality of first driving terminals, second driving terminals, and third driving terminals arranged in the insulating body, wherein the plurality of neutral terminals, first driving terminals, second driving terminals, and third driving terminals are electrically insulated, respectively, and the shape of the plurality of the first driving terminals, the second driving terminals, and the third driving terminals are the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the continuation of U.S. application Ser. No. 15/774,185, filed May 7, 2018; which is the U.S. national stage application of International Patent Application No. PCT/KR2016/012644, filed Nov. 4, 2016, which claims priority to Korean Application No. 10-2015-0155177, filed Nov. 5, 2015, the disclosures of each of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a busbar, a motor, and a power transmission system including the same.

BACKGROUND ART

Generally, an electronic power steering (EPS) system is a system for securing steering safety of a vehicle, and allows easy handling by supplying power using a motor in a direction in which a driver steers the vehicle.

Such an EPS system may improve a steering performance and a steering feeling by controlling an operation of the motor according to a driving condition unlike a conventional hydraulic power steering (HPS) system.

Specifically, the EPS system controls an inverter to drive the motor according to driving conditions detected by a vehicle speed sensor, a torque angle sensor, a torque sensor, and the like of an electronic control unit (ECU). Accordingly, since a turning safety is secured and a rapid restoring force is provided, the driver may safely drive.

Recently, safety requirements have been increased in the field of vehicles. Accordingly, a technology in which a safety of a vehicle is secured even when some parts (ECU or inverter) of the EPS system are in impossible operation states is required.

DISCLOSURE Technical Problem

The present invention is directed to providing a busbar with which a plurality of three-phase circuits may be formed.

The present invention is also directed to providing a motor having a plurality of three-phase circuits which are independently controlled.

The present invention is also directed to providing a power transmission system in which a plurality of inverters control a motor.

Technical Solution

One aspect of the present invention provides a busbar including: an insulating body; a plurality of neutral terminals disposed on the insulating body; and a plurality of first driving terminals, second driving terminals, and third driving terminals disposed on the insulating body, wherein the plurality of neutral terminals, first driving terminals, second driving terminals, and third driving terminals are electrically insulated from each other, and the plurality of first driving terminals, second driving terminals, and third driving terminals have the same shape.

The insulating body may include insertion grooves in which the plurality of first driving terminals, second driving terminals, and third driving terminals are disposed.

The plurality of neutral terminals may have the same shape.

The plurality of first driving terminals, second driving terminals, and third driving terminals may be coplanar.

A radius of a curvature at one end of each of the plurality of first driving terminals, second driving terminals, and third driving terminals may be different from that of a curvature at the other end thereof.

The curvature of each of the plurality of first driving terminals, second driving terminals, and third driving terminals may be changed from the one end of each of the plurality of first driving terminals, second driving terminals, and third driving terminals toward the other end thereof.

Each of the plurality of first driving terminals, second driving terminals, and third driving terminals may include: a body portion; a connection portion connected to the body portion; and a terminal portion protruding from the body portion in a direction of a shaft.

The connection portion may include a first connection portion connected to one end of the body portion, and a second connection portion connected to the other end of the body portion.

The busbar may further include extension portions disposed between the connection portion and the body portion, wherein the extension portions may extend in a direction perpendicular to the direction of the shaft, and a length of the extension portion connected to the first connection portion may be different from that of the extension portion connected to the second connection portion.

The length of the extension portion connected to the first connection portion may be greater than that of the extension portion connected to the second connection portion.

A curvature of the body portion may be changed from one end of the body portion toward the other end thereof.

Another aspect of the present invention provides a busbar including an insulating body and a plurality of first, second, and third driving terminals disposed on the insulating body, wherein a diameter of a first virtual circle connecting one ends of the plurality of first, second, and third driving terminals is less than that of a second virtual circle connecting the other ends thereof.

The insulating body may include a first hole formed at a center of the insulating body, and a diameter of the first hole may be less than that of the first virtual circle.

Centers of the first hole, the first virtual circle, and the second virtual circle may be the same.

Still another aspect of the present invention provides a motor including a stator including a first coil set and a second coil set, and a busbar including a first terminal set electrically connected to the first coil set to constitute a first circuit, a second terminal set electrically connected to the second coil set to constitute a second circuit, and an insulating body configured to fix the first and second terminal sets, wherein each of the first terminal set and the second terminal set includes at least one first driving terminal, at least one second driving terminal, and least one third driving terminal, and the first driving terminal, the second driving terminal, and the third driving terminal have the same shape.

A curvature of each of the first driving terminal, the second driving terminal, and the third driving terminal is changed from one end of each of the first driving terminal, the second driving terminal, and the third driving terminal toward the other end thereof.

Yet another aspect of the present invention provides a power transmission system including: a motor including a first circuit and a second circuit; a first driving unit electrically connected to the first circuit; a second driving unit electrically connected to the second circuit; and a control unit configured to control the first driving unit and the second driving unit, wherein the first circuit includes a first coil set and a first terminal set configured to electrically connect the first coil set, and the second circuit includes a second coil set and a second terminal set configured to electrically connect the second coil set.

Advantageous Effects

According to embodiments, since a plurality of three-phase circuits can be formed in a single motor, reliability can be improved.

Since shapes of terminals are the same, a manufacturing cost can be reduced.

Since the terminal is formed in a spiral shape, the plurality of terminals can be densely disposed, and thus a size of the plurality of terminals can be reduced.

Since a power terminal is separately manufactured, a manufacturing process can be simplified.

Since the terminals having the same shape are assembled, a structure of an insulator can be simplified, and a productivity of an assembly process can be improved.

Useful advantages and effects of the present invention are not limited to the above-described contents, and may be more easily understood from specific embodiments of the present invention which will be described.

DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view illustrating a motor according to one embodiment of the present invention.

FIG. 2 is a view for describing a state in which a busbar and a stator according to one embodiment of the present invention are electrically connected.

FIG. 3 is a view for describing a three-phase circuit of the motor according to one embodiment of the present invention.

FIG. 4 is a view illustrating a modified example of FIG. 3.

FIG. 5 is a view for describing an arrangement of a plurality of neutral terminals according to a circuit of FIG. 4.

FIG. 6 is a view for describing a shape of a driving terminal.

FIG. 7 is a view for describing an arrangement of a plurality of driving terminals.

FIG. 8 is a plan view of FIG. 7.

FIG. 9 is a block diagram of a power transmission system according to one embodiment of the present invention.

FIG. 10 is a view illustrating a modified example of FIG. 9.

MODES OF THE INVENTION

While the present invention may be modified in various ways and take on various alternative forms, specific embodiments thereof are shown in the accompanying drawings and described in detail below as examples. However, there is no intent to limit the present invention to the particular forms disclosed. On the contrary, the present invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the appended claims.

It should be understood that, although terms “first,” “second,” and the like may be used herein to describe various elements, the elements are not limited by the terms. The terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element without departing from the scope of the present invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Terms used in the present specification are merely used to describe exemplary embodiments, and are not intended to limit the embodiments. An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. In the present specification, it should be understood that the terms such as “including,” “having,” and “comprising” are intended to indicate the existence of features, numbers, steps, actions, components, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, components, parts, or combinations thereof may exist or be added.

In the description of embodiments, when an element is referred to as being “on or under” another element, the term “on or under” refers to either a direct connection between two elements or an indirect connection between two elements having one or more elements formed therebetween. In addition, when the term “on or under” is used, it may refer to a downward direction as well as an upward direction with respect to an element.

Hereinafter, embodiments will be illustrated in detail with reference to the accompanying drawings, and components that are the same or correspond to each other regardless of reference numerals will be referred to by the same or similar reference numerals, and redundant descriptions thereof will be omitted.

FIG. 1 is a cross-sectional view illustrating a motor according to one embodiment of the present invention.

Referring to FIG. 1, a motor 100 according to one embodiment of the present invention includes a housing 110, a stator 140 disposed in the housing 110, a rotor 130, a rotating shaft 150, and a busbar 160.

The housing 110 may accommodate the stator 140 and the rotor 130. The housing 110 may further include a cooling structure (not shown) to easily dissipate internal heat thereof. The cooling structure may be an air or water cooling structure, but is not limited thereto.

The stator 140 is inserted into an inner space of the housing 110. The stator 140 may include a stator core 141 and coils 142 wound around the stator core 141. The stator core 141 may include a plurality of divided cores. However, the stator core 141 is not limited thereto, and may also be integrally formed.

The rotor 130 may be disposed to rotate with respect to the stator 140. That is, the rotor 130 may rotate inside the stator 140. A rotor magnet 132 may be installed on an outer circumferential surface of the rotor 130.

The rotating shaft 150 may be coupled to a central portion of the rotor 130. Accordingly, the rotor 130 and the rotating shaft 150 may rotate together. The rotating shaft 150 may be supported by a first bearing 171 disposed at one side thereof and a second bearing 172 disposed at the other side thereof.

The busbar 160 may include a plurality of terminals electrically connected to the coils 142 wound around the stator 140 and configured to connect a U-phase, a V-phase, and a W-phase. A power terminal 164 of the busbar 160 may be exposed at the outside to be electrically connected to an external power or inverter.

FIG. 2 is a view for describing a state in which a busbar and a stator according to one embodiment of the present invention are electrically connected, FIG. 3 is a view for describing a three-phase circuit of the motor according to one embodiment of the present invention, FIG. 4 is a view illustrating a modified example of FIG. 3, and FIG. 5 is a view for describing an arrangement of a plurality of neutral terminals according to a circuit of FIG. 4.

Referring to FIG. 2, the stator 140 may include a plurality of divided cores 141 a and a plurality of coils 142 wound around the divided cores 141 a. The coil 142 may include one end 142 a and the other end 142 b which extend from the divided core 141 a in a direction of a shaft (a longitudinal direction of the rotating shaft). The one end 142 a may be a point from which coil winding starts, and the other end 142 b may be a point at which the coil winding ends. However, the one end 142 a and the other end 142 b are not limited thereto. For example, the one end 142 a may be a position at which coil winding ends, and the other end 142 b may be a position from which the coil winding starts.

The one end 142 a of each of the plurality of coils 142 may be electrically connected to a neutral terminal 162, and the other end 142 b may also be electrically connected to any one of driving terminals 163.

The busbar 160 may include an insulating body 161, a plurality of neutral terminals 162, and a plurality of driving terminals 163.

The insulating body 161 electrically insulates the plurality of neutral terminals 162 from the plurality of driving terminals 163. The insulating body 161 may include a plurality of insertion grooves 161 b in which the plurality of driving terminals 163 may be installed. The neutral terminal 162 is integrally injected with the insulating body 161 as example, but is not limited thereto. A material of the insulating body 161 is not specifically limited as long as the material has an insulating property. For example, the insulating body 161 may be formed by injection-molding a plastic resin.

The plurality of insertion grooves 161 b may be formed to have a predetermined distance to electrically insulate the driving terminals 163. A distance between the insertion grooves 161 b may be 0.5 mm to 2.0 mm, but is not limited thereto. The plurality of insertion grooves 161 b may have the same spiral shape. The insulating body 161 may have a circular plate shape in which a first hole 161 a is formed in a center thereof, but is not limited thereto.

The neutral terminal 162 may serve to connect neutral points of the plurality of coils 142. Here, the neutral terminal 162 may include the plurality of neutral terminals 162 which are electrically insulated. Accordingly, the motor 100 may include a plurality of neutral points, and the plurality of neutral points may be electrically insulated.

The plurality of driving terminals 163 may be connected to a power terminal 164. That is, the driving terminal 163 may be structurally separated from the power terminal 164. In such a structure, an inverter may be directly connected to an upper side of the busbar 160, and the structure of the power terminal 164 may be suitably changed according to a structure of the motor. However, the structure of the power terminal 164 is not limited thereto and may also be a power cable type. The power terminal 164 may include a plurality of connection fins 164 b electrically connected to the plurality of driving terminals 163 and a fixed part 164 a at which the connection fins 164 b are disposed.

The plurality of driving terminals 163 may serve to supply three-phase power to the coil 142. A three-phase circuit may be formed by electrically connecting the terminals of the busbar 160 and the coils 142

The plurality of driving terminals 163 may include a plurality of first driving terminals UT1 and UT2, second driving terminals VT1 and VT2, and third driving terminals WT1 and WT2. The first driving terminals UT1 and UT2 may be U-phase terminals, the second driving terminals VT1 and VT2 may be V-phase terminals, and the third driving terminals WT1 and WT2 may be W-phase terminals.

The U-phase terminals UT1 and UT2 may include a first U-phase terminal UT1 and a second U-phase terminal UT2, the V-phase terminals VT1 and VT2 may include a first V-phase terminal VT1 and a second V-phase terminal VT2, and the W-phase terminals WT1 and WT2 may include a first W-phase terminal WT1 and a second W-phase terminal WT2. In such a configuration, a plurality of three-phase circuits may be formed in the motor. However, the number of terminals is not limited.

Referring to FIGS. 3 and 4, the motor may include two independent three-phase circuits. A first circuit may be formed by connecting the first U-phase terminal UT1, the first V-phase terminal VT1, and the first W-phase terminal WT1 to a plurality of coils U1, U3, V1, V3, W1, and W3.

The second circuit may be formed by connecting the second U-phase terminal UT2, the second V-phase terminal VT2, and the second W-phase terminal WT2 to a plurality of coils U2, U4, V2, V4, W2, and W4. The first circuit may be an independent circuit connected by a first neutral point N1, and the second circuit may be an independent circuit connected by a second neutral point N2.

Here, a set of coils constituting the first circuit may be defined as a first coil set U1, U3, V1, V3, W1, and W3, and a set of coils constituting the second circuit is defined as a second coil set U2, U4, V2, V4, W2, and W4.

Referring to FIG. 4, a motor may also include four neutral points N1 to N4. A first circuit may include a first neutral point N1 and a second neutral point N2, and a second circuit may include a third neutral point N3 and a fourth neutral point N4. A three-phase circuit may also have more neutral points as necessary.

Referring to FIG. 5, four neutral terminals 162 may be disposed to include four neutral points which are electrically insulated. Here, the neutral terminals 162 may have the same shape. Specifically, the neutral terminal may include a body portion 1621 having a curvature, an extension portion 1622 bent in the direction of the shaft, and a connection portion 1623.

However, the neutral terminal is not limited thereto. Two neutral terminals 162 may also be disposed to include two neutral points as illustrated in FIG. 3, and shapes thereof may also be different.

FIG. 6 is a view for describing a shape of a driving terminal, FIG. 7 is a view for describing an arrangement of a plurality of driving terminals, and FIG. 8 is a plan view of FIG. 7.

Referring to FIG. 6, each of the plurality of driving terminals 163 may include a body portion 1631, a connection portion 1634 connected to the body portion 1631, and a terminal portion 1635 protruding from the body portion 1631 in the direction of the shaft.

The body portion 1631 extends in a predetermined length to connect a plurality of connection portions 1634. The body portion 1631 may have a strip shape having a curvature. A radius of the curvature of the body portion 1631 may change from one end 1632 toward the other end 1633.

The body portion 1631 may have a spiral shape. Here, the spiral shape may be defined as a shape in which a radius of a curvature changes from the one end 1632 toward the other end 1633. A radius of the curvature may increase from the one end 1632 toward the other end 1633. However, the radius of the curvature is not limited thereto, and may also decrease from the one end toward the other end. The radius of the curvature at the one end 1632 is 20 mm, and a radius of the curvature at the other end 1633 may be 30 mm, but the radii are not limited thereto.

As described above, the plurality of terminals configured to connect phases are disposed in the motor according to the embodiment as described above. Accordingly, the number of terminals may increase to two times that of a conventional motor. Such a spiral shape may be advantageous for arranging the plurality of terminals in a limited space. A thickness of the body portion 1631 may range from 0.5 to 2.0 mm, but is not limited thereto.

The connection portion 1634 is a portion electrically connected to the coil. The connection portion 1634 may have a hook or Y shape, but is not limited thereto. The connection portion 1634 may include a first connection portion 1634 a connected to the one end 1632 of the body portion 1631 and a second connection portion 1634 b connected to the other end 1633 of the body portion 1631. The number of connection portions may be increased as necessary.

The terminal portion 1635 may protrude from the body portion 1631 in the direction of the shaft. The terminal portion 1635 may be connected to an external power or an inverter to supply power to the connection portion 1634.

An extension portion 1638 may be formed between the body portion 1631 and the connection portion 1634.

The extension portion 1638 may include a first bent portion 1637 protruding in the direction of the shaft and a second bent portion 1636 extending from the first bent portion 1637 in a direction perpendicular to the shaft. A height of the connection portion 1634 may be determined according to that of the first bent portion 1637. The terminal portion 1635 may also be disposed on the extension portion 1638.

A length of the second bent portion 1636 connected to the first connection portion 1634 a may be longer than that of the second bent portion 1636 connected to the second connection portion 1634 b. Such a structure may expose the connection portion at the outside of the insulating body to allow the connection portion to be electrically connected to the coil in a spiral type arrangement.

Referring to FIG. 7, all of the plurality of U-phase terminals UT1 and UT2, the V-phase terminals VT1 and VT2, and the W-phase terminals WT1 and WT2 may have the same shape. In this case, since the terminals do not need to be separately manufactured, there is an effect in that a manufacturing cost is reduced, and there is an advantage in that an assembly is simplified.

All of the plurality of U-phase terminals UT1 and UT2, V-phase terminals VT1 and VT2, and W-phase terminals WT1 and WT2 may be disposed to be coplanar. That is, the plurality of U-phase terminals UT1 and UT2, V-phase terminals VT1 and VT2, and W-phase terminals WT1 and WT2 may be connected to the coils at the same height.

The first U-phase terminal UT1, the first V-phase terminal VT1, and the first W-phase terminal WT1 may be a first terminal set 163 a constituting the first circuit, and the second U-phase terminal UT2, the second V-phase terminal VT2, and the second W-phase terminal WT2 may be a second terminal set 163 b constituting the second circuit.

Referring to FIG. 8, a diameter of a first virtual circle CL1 which connects the one ends 1632 of the first U-phase terminal UT1, the second U-phase terminal UT2, the first V-phase terminal VT1, the second V-phase terminal VT2, the first W-phase terminal WT1 and the second W-phase terminal WT2 may be less than that of a second virtual circle CL2 which connects the other ends 1633 thereof. Accordingly, the first U-phase terminal UT1, the second U-phase terminal UT2, the first V-phase terminal VT1, the second V-phase terminal VT2, the first W-phase terminal WT1 and the second W-phase terminal WT2 may be densely disposed in a limited space.

Here, a diameter of the first hole 161 a formed in the insulating body may be less than that of the first virtual circle CL1, and the first hole 161 a, the first virtual circle CL1, and the second virtual circle CL2 may have the same center P. In addition, all angles θ between virtual lines L1 to L6 from the center P to the one ends 1632 of the terminals may be the same.

FIG. 9 is a block diagram of a power transmission system according to one embodiment of the present invention, and FIG. 10 is a modified example of FIG. 9.

Referring to FIG. 9, a power transmission system according to one embodiment of the present invention includes a motor 100 having a first circuit 100 a and a second circuit 100 b, a first driving unit 30 electrically connected to the first circuit 100 a, a second driving unit 40 electrically connected to the second circuit 100 b, and a control unit 10 configured to control the first driving unit 30 and the second driving unit 40.

The first circuit 100 a and the second circuit 100 b of the motor 100 having the same configurations as described above may be included in the power transmission system. The first circuit 100 a includes a first coil set and a first terminal set configured to electrically connect the first coil set, and the second circuit 100 b includes a second coil set and a second terminal set configured to electrically connect the second coil set.

The first terminal set may include a first U-phase terminal UT1, a first V-phase terminal VT1, and a first W-phase terminal WT1, and the second terminal set may include a second U-phase terminal UT2, a second V-phase terminal VT2, and a second W-phase terminal WT2.

Each of the first driving unit 30 and the second driving unit 40 may be an inverter configured to convert direct current (DC) power supplied from a power source 20 into three-phase power. The power source 20 may be a vehicle battery.

The first driving unit 30 may be connected to U-phase, V-phase, and W-phase of the first circuit 100 a to supply three-phase power to the first circuit 100 a, and the second driving unit 40 may be connected to U-phase, V-phase, and W-phase of the second circuit 100 b to supply three-phase power to the second circuit 100 b. That is, the first driving unit 30 and the second driving unit 40 may independently drive the first circuit 100 a and the second circuit 100 b. Accordingly, even in a case in which any one of the first driving unit 30 and the second driving unit 40 does not operate, the motor 100 may be operated by the remaining driving unit. Accordingly, the power transmission system may be suitable for the field such as a vehicle demanding a high level of safety.

The control unit 10 may output a control signal to the first driving unit 30 and the second driving unit 40 according to driving conditions detected by a vehicle speed sensor, torque angle sensor, torque sensor, and the like. The control unit 10 may be an electronic control unit (ECU). Referring to FIG. 10, the control unit 10 may include a first control unit 11 configured to control the first driving unit 30 and a second control unit 12 configured to control the second driving unit 40. In this case, even in a case in which any one of the first control unit 11 and the second control unit 12 does not operate, the motor may be controlled by the remaining control unit. 

The invention claimed is:
 1. A motor comprising: a housing; a stator disposed in the housing; a rotor disposed in the stator; a shaft disposed in the rotor; and a busbar disposed on the stator, wherein the busbar includes an insulating body, a plurality of neutral terminals disposed in the insulating body, and a plurality of driving terminals disposed in the insulating body, wherein the plurality of driving terminals includes a first terminal set and a second terminal set electrically disconnected from the first terminal set, wherein the first terminal set includes a first U-phase terminal, a first V-phase terminal, and a first W-phase terminal, wherein the second terminal set includes a second U-phase terminal, a second V-phase terminal, and a second W-phase terminal, wherein a diameter of a first virtual circle connected to a first end of each of the first U-phase terminal, the first V-phase terminal, and the first W-phase terminal is smaller than a diameter of a second virtual circle connected to a second end of each of the first U-phase terminal, the first V-phase terminal, and the first W-phase terminal, and wherein centers of the first virtual circle and the second virtual circle are identical.
 2. The motor of claim 1, wherein each of the first U-phase terminal, the second U-phase terminal, the first V-phase terminal, the second V-phase terminal, the first W-phase terminal, and the second W-phase terminal comprises: a body portion comprising the first end and the second end; a first connection portion connected to the first end of the body portion; and a second connection portion connected to the second end of the body portion, wherein each body of the second U-phase terminal, the second V-phase terminal, and second W-phase terminal is disposed between the first virtual circle and the second virtual circle.
 3. The motor of claim 2, wherein the first U-phase terminal, the first V-phase terminal, the first W-phase terminal, the second U-phase terminal, the second V-phase terminal, and the second W-phase terminal have the same shape.
 4. The motor of claim 3, wherein the first connection portion and the second connection portion protrude toward an outside of the second virtual circle.
 5. The motor of claim 4, wherein a curvature of each of the body portions of the first U-phase terminal, the first V-phase terminal, the first W-phase terminal, the second U-phase terminal, the second V-phase terminal, and the second W-phase terminal is changed from the first end toward the second end thereof.
 6. The motor of claim 5, wherein each of the body portions of the first U-phase terminal, the first V-phase terminal, the first W-phase terminal, the second U-phase terminal, the second V-phase terminal, and the second W-phase terminal has a spiral shape.
 7. The motor of claim 3, wherein each of the first U-phase terminal, the second U-phase terminal, the first V-phase terminal, the second V-phase terminal, the first W-phase terminal, and the second W-phase terminal comprises: a first extension portion disposed between the first connection portion and the body portion; and a second extension portion disposed between the second connection portion and the body portion, wherein the first extension portion and the second extension portion extend in a direction perpendicular to the direction of the shaft.
 8. The motor of claim 7, wherein a length of the first extension portion is longer than a length of the second extension portions.
 9. The motor of claim 2, wherein each of the plurality of neutral terminals has the same shape.
 10. The motor of claim 1, wherein the neutral terminals, the first terminal set, and the second terminal set are electrically insulated from each other.
 11. The motor of claim 1, wherein the insulating body includes a first hole formed at a center of the insulating body, wherein a diameter of the first hole is less than that of the first virtual circle, and wherein centers of the first hole, the first virtual circle, and the second virtual circle are identical. 